Microsoft’s Surface Pro tablet hits stores this weekend, more than three months after the less powerful RT version of the device went on sale.

Recent reviews of the Windows 8 Surface Pro have been mixed, with the device’s battery life and storage capacity among several areas of concern. Both issues were addressed by the general manager of the Surface team, Panos Panay, and a number of Microsoft engineers in an AMA (Ask Me Anything) session on Reddit on Wednesday.

Battery

According to a post on one of Microsoft’s official Twitter feeds a couple of months back, the battery life of the 10.1-inch Pro tablet is, to put it mildly, a bit feeble. The tweet said that the Pro tablet has “approximately half the battery life of the Surface RT” – in other words, about 4.5 hours.

In Wednesday’s AMA, the Microsoft team said it’d wanted to create a product that didn’t compromise on speed or performance.

“With that, we wanted to be the best notebook/laptop product in its class, but still deliver you the tablet form factor,” the team said. “This product is optimized in every way to take advantage of the full third generation core i5 it runs, yet give the best battery life.”

The response went on to say that if compared to a MacBook Air, “you will quickly see that pound for pound in battery size vs battery life, you will find optimizations that puts Surface best in its class. That said we picked a smaller battery to be sure we were able to give you the same performance and to keep it thin.”

That’s all well and good, but will it really be enough to help consumers forget that the Surface Pro’s tablet competitors – the 9.7-inch iPad, Amazon’s 8.9-inch Kindle Fire HD and Google’s Nexus 10 among them – claim battery time upwards of eight hours?

What might help is the team’s hint that some kind of external battery may be in the works, possibly as part of a thicker Touch or Type Cover. When asked during the AMA if there were any plans for such a product, the Surface team wrote, “That would require extending the design of the accessory spine to include some way to transfer higher current between the peripheral and the main battery. Which we did…”

Storage

Regarding the storage issue – which hit the headlines last week when Microsoft said the 64GB version of the Pro tablet would ship with only 23GB of storage space, while the 128GB version would have only 83GB of available space – the Surface team said during the AMA that these were in fact “conservative” estimates. “Our final production units are coming in with ~6-7GB additional free space,” the team wrote. The reduced capacity is down to the space taken up by the operating system and native apps.

But this extra space still leaves it way short of, for example, the 64GB iPad which gives users about 57GB of free space out of the box. Fortunately, those who do decide to pick up one of the new Surface Pro tablets in the coming months will be able to use the device’s microSDXC card slot to increase its storage capacity by up to 64GB.